Fuse



July 11, 1950 Filed Jan. 15, 1946 P. S. WILLIAMS ETAL FUSE 3 Sheets-Sheet 2 FIG. 3

FIG. 4

INVENTORS PHIL/P s. W/LL/A MS BEN w. SEWELL ATTORNEY y 1950 P. s. WILLIAMS ET AL 2,515,066

FUSE

Filed Jan. 15, 1946 3 Sheets-Sheet 3 FIG. 5

b, q 5; 0011. SPRING o E BELLEV/LLE SPRING 3 NIMUM o DEFLECTION INCREASE I N V EN TOR. PHILIP S. WILLIAMS BEN W. SEWELL ATTORNEY Patented July 11,1950

FUSE

.Application January 15, 1946, Serial No. 641,342

for use with armor piercing projectiles which is maintained in safecondition until impact of the projectile with the target, whereupon the fuze becomes cocked and thereafter fires only after the deceleration forces, sometimes called reverse setback forces, drop to a predetermined value.

Another object of the invention is to provide a fuze which is especially adapted for use in projectiles fired against concrete pill boxes in which itis desirable thatthe projectile be detonated only after ithas penetrated as far as possible into the target.

Another object'of the invention is to provide a fuze of thetype referred toabove which is simple and positive in operation, and which is easily produced in large quantities.

These and other objects of the invention will be evident from the following specification and the accompanying drawings, in which Fig. l is a longitudinal sectional view of the fuze in safe condition prior to firing of the projectile from a gun;

Fig. 2 is a longitudinal sectional view of the fuz e taken during flight of the projectile;

Fig. 3- is a longitudinal sectional View of the target but before firing of the fuze;

Fig. 4 is'a longitudinal sectional view of the fuze after maximum penetration of the target, showing the fuze elements in their firing positions; and

Fig. 5 is a graph showing, by a solid curved line, the snap action characteristic of the resilient means employed, the deflection vs. load characteristic of conventional spring means being shown by a dotted line.

In the preferred embodiment of the invention shown in the drawings, the fuze comprises a hollow outer body member in having internal shoulders H and I2. The forward end of the body member ID is provided with a pair of diametrically opposed radial bores I3 in which are mounted a pair of detent housings I4 closed at their outer ends and containing centrifugal detents l-5 which are urged inwardly by coil springs Hi. The outer ends of the bores l3 are staked at [1 to retain the detent housings l4 in place.

The rear end of the body member I0 is inwardly flanged at It to retain a disc-shaped member l9 having an axial bore 20 which contains a percussion detonating charge 2| for detonating the 1 Claim. (Cl. 1 02.79)

main explosive charge of the projectile with which the fuze is used. The member 19 is retained against forward movement relative to the body member ID by means of a washer 22 which is positioned between the shoulder H and the member l9, and which has an inwardly extending flange 23 which serves to define the limit of forward movement of an inertia member 24 positioned within the housing by means of its cooperation with an external flange 25 on the rear end of the inertia member.

The inertia member 24, with the exception of its flange 25, is of a smaller outer diameter than the inner bore of the flange 23 and has a forwardly extending hub 26 of diminished diameter to fit within the opening defined by shoulder H! in the forward portion of the body member Hi adjacent the bores I3. The rear surface of the inertia member 24 is provided with an axial recess 21 in which is mounted a thin metal washer 28 by means of a retainer ring 29 which is held in place by an inwardly extending flange 30 on the inertia member. Resilient means comprising a plurality of resilient washers 3| of the Belleville type are mounted on the hub 26 of the inertia member between the forward surface of the inertiamember and the shoulder 12 of the body member so as to urge the inertia member rearwardly toward its initial position as shown in Fi 1.

The inertia member 24 is provided with an axial bore 32 in which is positioned a firing pin 33 having a disc-shaped head 34 on its forward end, the head having an outer diameter approximately equal to that of the hub 26. The rear end of the firing pin 33 is formed with a shoulder 35 and a pointed detonator contacting portion 36 which initially is positioned within the central opening in the washer. The diameter of the firing pin and the diameter of the opening 280. in the washer 28 are such that the washer 28 initially abuts the shoulder 35 of the firin pin when the inertia member is in its initial position and thereby prevents rearward movement of the firing pin.

In operation, with the elements of the fuze in their unarmed positions as shown in Fig. 1, the inertia member 24 is retained in its initial position by the resilient washers 3| and by the abutment of the forward end of the hub 26 with the centrifugal detents [5 which also abut the head 34 of the firing pin to prevent rearward movement of the firing pin. The shoulder 35 at the rear end of the firing pin is in contact with the disc 28 which alone is of sufficient strength to 3' retain the firing pin against rearward movement except as will be explained presently.

When the projectile provided with the fuze is fired from a gun, the rotation of the projectile during fiight sets up centrifugal force which acts on the detents l5 and throws them outwardly into the positions in which they are shown in Fig. 2 so that they no longer lie in the path of rearward movement of the firing'p'in head 34 and also are out of the path of forward movement of the hub 25 of the inertia member 24. During the flight of the projectile, the inertia member 24 is retained in its initial position by the resilient washers 3! which oppose=any tendencyof the inertia member to move forward unde'rthe small forces of reverse setback whichnarise as the thrown with considerable force into the detonatprojectile slows down during its flight through the air. The engagement of the washer'28with the shoulder 35 on the rear end of the firing'pin 33 prevents rearward movement of the firing pin to-a firing position.

Upon-impact of the projectile with a target such as a concrete structure, the immense forces of reverse setback whichactupon the elements of ithefuzeimme'diately upon contact'causes the inertia member'24 to overcome the resistance of the-resilient washers 3| and move forwardly until the forward end of the hub 26 lies against the rear surface of the head of the firing pin. The

forward movement of the inertia member also carries the washer 28 forwardly over the shoulder 3-5 of the firing pin to the position shown inFig. 3, bending the margin of .the openin in the washer rearwardly.

As soon as the forces of deceleration or reverse setback decrease below .a predetermined value as therpro jectile comes to a stop, the resilient washers 3| -move the inertia member 24 rearwardly and due tothe grasping of the firing pin 33 by the bent -marginal.portion of the opening in washer .28, the firing .pin is moved rearwardly with the inertia member intofiring contact with the detonator 2l to detonate the projectile.

It is desired particularly to emphasize that the Bllevi'lle type Washers '31 are employed for the resilient means 'for the reason that they have a peculiar snap action characteristic, as indicated by'the solid line and curve in the graph ofFigff). A coil compression spring has a straightline de- "fiection vs. load characteristic, as indicated by a dotted line on said graph for comparison."I'hus, when reverse set-back reaches a predetermined minimum value, the firing pin 33 is immediately ing charge 2|.

It is obvious that the present invention provides an efficient fuze for armor piercing projectiles which detonates the propectile only after the projectile has substantially decreased its forward movement after impact with the target.

It is to be understood that there is herein described a preferred embodiment of the invention and that the invention is susceptible of nu- *merous variations therefrom without departing from the spirit of the invention as defined by the "appended claim.

What is claimed is Inrafuzeforusewith rotating projectiles, a, firting'pinih'avingfiring and safe positions, an inertia member having an unarmed position and an armed position to'which it is movable by forces of reverse setback, resilient means resisting movement of said inertia member out of said unarmed position under the influence of reverse (setback forces smaller than .a predetermined (magnitude, means normally positively retaining said firing ,pin; and said-inertiazmember insaid safe position andsaid unarmed position, respectively, said last named means being movable to an inoperative position by-centrifugal force incidenbtorotation of the proj ectile -in =fii-ght, and :means i-carried .by saidpinertialmemberfor retaining said firing pin in a safe position while said inertia member is in z-its unarmed :position 'and for snapping said :flring pin to its firingposition upon movement of said :-inertia --member to its armed position and subsequentireturnof the inertia memberto its unarmedeposition under.- the. influence of said ,re-

siiient means after the force of reverse isetback diminishes ibelow said .'predetermined, magnitude, said :l=ast rm'entioned means :consisting of a plurality of stacked resilient-washers.

;-.BHILIP 'S. .::-BEN W.

LREFERENCES QIT ED following references are o'f record in "the fi-leaof this 1patent:

UNITED STATES PATENTS Number .Name Date Re 1 5,933 Carey Oct. 21,1924 1 2%;070 =.Gathmann -Mar.=4, 1919 1,309,768 Newell July 15, 11919 1311,67 8 Cartwright J 11:13129, 1919 I '.;2;l62,2l9 Hay. v. June. 20, ,1939 

